Anna Nicole Smith, the flamboyant American model and actor best known for her marriage to a billionaire six decades her senior, died last night after collapsing in a hotel room in Florida. The 39-year-old former Playboy playmate of the month was found unconscious by her private nurse at the Seminole Hard Rock Hotel near Fort Lauderdale. Smith, who had a history of drug problems, was taken to the nearby Hollywood Memorial hospital where she was pronounced dead.

Seminole's police chief, Charlie Tiger, said a bodyguard had tried in vain to resuscitate her with a heart massage. Sources told the cable TV entertainment network E! that Smith had been suffering from flu-like symptoms on her arrival at the hotel on Monday. On Wednesday, she apparently fell in the bathroom and hit her head but said she felt fine and went back to bed. Yesterday, the sources said, the nurse tried to wake her from a midday nap but found her unresponsive with her eyes dilated. A postmortem today is expected to determine the cause of death.

Smith had been staying at the hotel, owned by the native American Seminole tribe, with her new husband and lawyer, Howard K Stern, who claims to be the father of her six-month-old daughter, Dannielynn.

Another of Smith's attorneys, Ronald Rale, told reporters: "It's as shocking to me as to you guys. Howard, obviously, is speechless and grieving."

He added: "Poor Anna Nicole. She's been the underdog. She's been besieged ... and she's been trying her best and nobody should have to endure what she's endured."

Smith was no stranger to lawsuits. At the time of her death she was involved in a paternity suit with photojournalist, Larry Birkhead, a former boyfriend, although Mr Stern is listed on Dannielynn's birth certificate as the father.

Mr Birkhead last night filed an emergency injunction to try to gain custody of the child, who is said to be in the Bahamas, where she was born.

Dannielynn's birth was mixed with tragedy and mystery when Smith's 20-year-old son Daniel died in her hospital room of an apparent drugs overdose three days after the birth last September.

Smith's most high-profile court battle, however, was the feud with the family of her ex-husband, J Howard Marshall, over his multibillion dollar fortune. She met the oil baron in 1991 when she was working as a stripper in a Houston nightclub and they married three years later, when she was 26 and he was 89.

In an interview with ABC television two years ago, Smith recalled her first meeting with Marshall. "He had no will to live and I went over to see him," she said. "He got a little twinkle in his eyes, and he asked me to dance for him. And I did."

The marriage lasted 13 months before Marshall died, sparking a bitter fight with his family over the money. Smith said he promised her half of his fortune if she married him, and she was initially awarded $474m, a decision overturned when a Texas court decided Marshall's son, E Pierce Marshall, was the sole heir.

In 2005, the case reached the supreme court, which ruled unanimously that she should be allowed to pursue her claim in a federal court. The issue was still outstanding at the time of her death.

Last night, the Marshall family released a statement saying: "[We were] shocked by the untimely death of Anna Nicole Smith. We wish to express our sympathies to her family in this difficult time."

Hugh Hefner, Playboy's founder, paid tribute to Smith, who he said was one of his magazine's most popular playmates. "I'm very saddened to learn about Anna Nicole's passing. She was a dear friend who meant a great deal to the Playboy family and to me personally," he said.

Smith's sister, Donna Hogan, also issued a statement. "We feel that the death of her son left her deeply saddened, a sadness she hid from everyone," she said. "As a mother of three children I am anguished by this tragic event and the fact that her new baby, Dannielynn Hope, is now without a mother."

Smith had acknowledged problems with drug addiction and checked into the Betty Ford Clinic for a spell in the mid-1990s. It is not known why a female nurse, who was privately employed, accompanied her during her holiday in Florida.

"The nurse in her room called the hospital operator at 1.38pm and we responded within minutes," Mr Tiger said. "At 1.45pm, a bodyguard administered CPR."

He said detectives from the Broward County crime laboratory were examining her hotel room, but that there was no indication of foul play.

Smith was staying in Florida with Mr Stern, whom she wed in a civil ceremony in the Bahamas after her daughter's birth. The pair were reportedly looking to buy a boat together, but Mr Tiger said he could not speculate on the reason for their stay. "It's a beautiful hotel and a lot of people come here to relax," he said. "She was a frequent patron here."

Backstory

Anna Nicole Smith was born Vickie Lynn Hogan and grew up in the Texas town of Mexia. The model and actress, who capitalised on her resemblance to Marilyn Monroe, won fame as the face of Guess jeans and was named Playboy magazine's Playmate of the Year in 1993. The following year, she appeared in The Hudsucker Proxy and Naked Gun 33 1/3: The Final Insult. She was most famous for her relationship with the oil billionaire, J Howard Marshall, whom she met dancing at a Houston strip club. Eyebrows were raised when the couple married in 1994. She was 26 and he was 89. He died the next year and Smith began a battle with his family over his estate, valued by Forbes.com at $1.6bn (£810m). In May 2006 the US supreme court ruled that Smith could pursue her case in federal court. Her son, Daniel, 20, died in the Bahamas last year in what was believed to be a drug-related death. Dan Bell